i took these photo's last year and they just got worse. this year there is just a bit of this.
last year we had an unusually wet spring.
this year i have used 20/20 a fungicide, an all purpose fertilizer and 'spray 'n' grow' a nutrient supplement for plants. any ideas?
thanks,
debi z and little franklin
picture #2
Definitely fungal leaf spot. Although unsightly, it's not usually harmful to the plant. However, my experience is that if it goes unchecked it CAN weaken the plant to other diseases and/or rot. We have a big problem with leaf spot in the PNW because of how much it rains, along with the humidity during spring and summer.
Fungal leaf spot is a soil-born disease, meaning it hides out in the soil and gets splashed up onto the leaves when it rains. It then spreads from small spots, to larger spots and/or streaks and eventually kills the foliage.
The most effective thing you can do to limit your leaf spot is to do a thorough fall (and periodic spring) clean up. Remove any dead foliage around the plants, as well as clean up any spent flowers or other plant matter around the area. These should be thrown away, not put onto a compost pile because this will just harbor the fungus and spread it around to other areas of your garden. The fungus can also spread from your hands or cutting tools to other irises, so be sure to disinfect before touching other plants.
The use of two different fungicides is recommended, so that the plants don't build up an "immunity" to it. Alternate the fungicides every two weeks. Be sure to start spraying when you start to see new foliage, and continue through the growing season. Adding a sticker-spreader to the fungicide is also recommended because the iris leaves are slick and this will help it to stick better.
I also find that leaf spot is more prevalent in areas where my irises are closer together. I was told that this is because the air can't circulate as well and it creates a warm "breeding ground" for the fungus. Make sure your irises have plenty of space by dividing them every 3-4 years.
In my experience, even if you follow all of these recomendations, you will still have SOME leaf spot, especially during particularily rainy and/or humid seasons. However, these steps should greatly reduce your problem and keep your foliage looking healthy and green.
flowerfrenzy, your a dear. thank you for all this wonderful information. its good to hear that i was doing the right thing by spraying with a fungicide. i also use a sticking agent, so i have that covered. now i just need to get another fungicide i like.
thank you again and i'm off to the garden to get some watering done.
debi z
In addition to flowerfrenzy's fine information, avoid overhead watering of bearded irises. As mentioned, water will tend to splash fungal spores onto the leaves and spread leaf spot around. Bearded irises rarely require supplemental water at all, but if you feel the need to provide it, drip irrigation or soaker hoses are best.
thank you laurie. does this virus also effect daylilies? i have some that are brown/rust and yellow, mostly down the center of the leaves. they deteriorate and the brown/rust spots become holes.
thanks debi z and franklin too.
Another thing you can do to avoid spread of pathogens is to put a layer of mulch on top of your soil. This way rain and watering will limit back splash. If soil is exposed much more risk of soil pathogens being thrown back up
I think the rust spots you're referring to is actually daylily rust, which is a different disease alltogether and one I know little to nothing about! Better head to the daylily forum and ask your question there.
The mulch might help with the splashing up of the fungus, but if you do that, be careful not to cover over the rhizomes too deeply. Mulch + Rain + Humidity= Rot!
